Production of alkylated phenols



UNITED STATES PATENT OFFICE PRODUCTION or ALKYLATED masons Donald R. Stevens, lswissvale, and Joseph E.

Nickels, Pittsburgh, Pa.,-assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application April 11, 1938, Serial No. 201,458

6 Claims. (01. 260-624) This invention relates to the production of bined with sulfuric acid, particularly concentrated alkylated phenols; and it comprises a method for sulfuric acid, have the property of decreasing the alkylation of phenolic compounds with olefins the catalytic effect of the latter on the polyin the presence of a sulfuric acid catalyst, in merization of olefins and that the mixture of which the polymerizing action of the sulfuric sulfuric acid and alkali sulfate thus produced 5 acid on the olefin is substantially suppressed by is an effective catalyst in the alkylation of pheincorporating in the sulfuric acid a substantial nols with olefins. Thus by carrying out the amount of a sulfate of an alkali such as sodium, alkylation of phenolic materials with olefins acpotassium or ammonium sulfate; all as more cording to the method of our invention, in which 10 fully hereinafter set orth and as claimed. the phenolic material and the olefin are con- 10 The alkylated phenols have found extended tacted with a catalyst comprising concentrated application in the prevention of oxidatiohal sulfuric acid and a sulfuric acid salt of an alkali changes in various organic materials such as such as a sodium, potassium or ammonium salt, various petroleum and other hydrocarbon prodwe are able to control the amount of polymer 16 ucts, rubber and the like. They have been found f rm d, n p i la y, n cases f alkylation particularly suitable for use as antioxidants for of phenolic compounds which are difiicult to gasolines produced bycracking petroleum oil or alkylate, we are able to carry out the alkylation by polymerizing normally gaseous hydrocarbons, at elevated temperatures under pressure without which gasolines contain substantial amounts of the formation of excessive amounts of olefin-poly- 20 constituents having a tendency to oxidize'and mu. :0 form unde ir bl gums, The degree to which the polymerizing action In general the alkylated phenols may be proof the sulfuric acid is suppressed depends to duced directly by treating a suitable phenol or some extent upon the concentration of the acid, I phenol substitution product with an olefin, parthe percentage of alkali sulfate added and the ticularly an iso-olefin such as isobutylene or isotemperature of reaction. For example, with any 25 amylene, in the presence of sulfuric acid at temven concentration o acid. the amount of S111- peratures up to about 70 C. However, in the fate added should be increased in general with production of alkylated phenols from some phehigher e p u es of reaction in Ord to D- nolic compounds which are particularly stable press the polymerization to the same degree.

or which have relatively high melting points, When using concentrated sulfuric acid, effective 30 it is sometimes necessary or desirable to carry upp n f p lymeriz i n may be obtained out the alkylation reaction at elevated'temperaby incorporating therein amounts of alkali sultures under pressure in order to effect satisfate as low as 10 per cent of the weight of the factory alkylatlon in a reasonable length of time. acid. Additions of sulfate in such low amounts Whether the reaction is carried out at temperaare particularly effective when operating in the 35 tures of 70 C. or less, or at elevated temperalower temperature ranges such as between 70 tures under pressure, more or less of the olefin and 100? C. When it is found necessary or deused is polymerized instead of reacting with sirable to effect the alkylation at an elevated the phenolic compound to produce an alkylated temperature under pressure, that is to say at 40 phenol. This polymerization of the olefin is, temperatures above about 100 0., effective sup- 40 as a rule, not objectionable, provided the polypression of the polymerization of the olefingenmers are not formed in an excessive amount. erally requires the use of larger percentages of However, particularly in those cases where the sulfate. When operating at temperatures up to alkylatlon is carried out at higher temperatures about 150 C. best results are usually obtained and under pressure, the amount of olefin polywith concentrations of alkali sulfate up to about 45 merized is often quite large and may be so large 60 per cent of saturation, although at higher as to affect adversely the yield of alkylated phetemperatures amounts of alkali sulfate up tono]. It is therefore often desirable that the the saturation limit may be used. It is generpolymerization of the olefin be suppressed during ally undesirable to use an amount of alkali sulthe alkylation of a phenolic material with an fate in excess of that required to effect maxi- 50 olefin in the presence of a sulfuric acid catalyst. mum suppression of polymerization at any given This result is accomplished by the method of our temperature, as such excess will tend to decrease invention. 7 the alkylation of the phenol.

Thisinventionis predicated upon the discovery The alkali sulfate may be added as such to that the alkali salts of sulfuric acid when comthe sulfuric acid or the sulfuric acid may be 55 treated with a compound of the alkali such as sodiumjpotassium, or ammonium hydroxide or carbonate, to form in solution in the acid the required amount of the alkali sulfate. In most cases it is more convenient simply to add sodium, potassium or ammonium sulfate to the sulfuric acid. When concentrated sulfuric .acid is used as the catalyst, ammonium sulfate added to the sulfuric acid solution has given good results.

The sulfuric acid solution used may, of course, be a solution of any concentration which is useful to catalyze the alkylation of a phenol with an olefin. With the higher concentrations of acid which normally tend to produce more polymerization, the addition of the alkali sulfate according to the method of our invention is particularly useful. We have found, for example, that the addition of an alkali sulfate to a sulfuric acid solution containing 80 per cent to 100 per cent H2804, in amounts up to' the saturation limit, produces particularly satisfactory catalysts. Commercial concentrated sulfuric acid about per cent saturated with ammonium sulfate, for example, produces good yields of alkylated phenols without excessive polymerization when used at temperatures as high as 150 C.

The alkali sulfate-sulfuric acid mixture is generally used in relatively small amounts. Amounts corresponding to about 5 per cent by weight of the phenolic material being alkylated have given good results. However, larger or smaller amounts may be used when desirable with modified conditions of temperature and time of reaction.

While the method of this invention may be applied to the'alkylation of a phenolic material with substantially any iso-olefln to prevent excessive polymerization of the olefin, it is particularly' useful in the alkylation of phenolic materials with isobutylene. Isobutylene has a marked tendency to polymerize in the pre'-'ence of sulfuric acid, particularly at temperatures above about C. butylation of phenolic materials at temperatures above this point in order to accelerate the reaction, particularly with compounds which are difficult to alkylate. In such cases, the isobutylene may tend to polymerize to the exclusion of the alkylation of the phenolic material. If, however, the reaction is carried out in the presence of a mixture of sulfuric acid and an alkali sullate, the polymerization can be sufficiently suppressed to permit the alkylation of the phenolic material.

For example, the alkylation of para-hydroxydiphenyl with isobutylene for the productionof 2,6-di-tertiary -butyl-4-phenyl phenol requires somewhat drastic reaction conditions in order to effect the reaction in a reasonable time. When it is attempted to carry out this reaction at temperatures above about 0., using concentrated sulfuric acid as the catalyst, the major part of the isobutylene is polymerized and very' little butylation of the hydroxy-diphenyl occurs.

On the other hand, by using concentrated sulfuric acid about 60 per cent saturated with an alkali sulfate, in amounts corresponding to about @butyle'ne were placed in a pressure vessel. cne vessel there was introduced commercial con- It is often useful to effect the tion of para-hydroxy-diphenyl in the presence of a plain sulfuric acid catalyst and in the presence of a sulfuric acid catalyst about 60 per cent saturated with ammonium sulfate. y

In each case 30 parts by weight of para-hydroxy-diphenyl and 80, parts by weight of iso- Into centrated sulfuric acid in an amount corresponding to about 5 per cent by weight of the parahydroxy-diphenyl, and a corresponding amount of commercial concentrated sulfuric acid about 60 per cent saturated with ammonium sulfate was placed in the other vessel. Both vessels were then heated to C. and maintained at that temperature for 70 minutes, the mixture in the vessel being constantly agitated. The vessels were then cooled rapidly. An oily liquid reaction product was then separated out, washed with dilute aqueous alkali solution and the washed product was fractionally distilled to separate the polymer fraction from the 2,6-di-tertiary-butyl- 4-phenyl phenol. para-hydroxy-diphenyl were also recovered and measured. The results obtained are shown in the following table:

H so H63? about i 4 u 53 Catalyst used alone rated with 01 04 Unreacted isobutylene .grams 3 l8. 3 Unreacted para-hydroxyaiiphenyl do. 3 7. 7 Liquid reaction product .d 108 89. 6 Polymer in reaction product ..do 58. 5 25. 0 Alkylated phenol in reaction product.do 37. 3 28. 8 isobutylene n polymer .percent 75.8 40.5 Isobutylene n alkylated phenol do 19. 6 18. 5 Polymer in liquid product '..do 54.1 27. 9 Alkylated phenol in liquid product .do. 34. 5 32. 2 Rat 0: Percent polymer in liquid product to percent alkylated phenol in liquid p 1 57 0. 87

It is readily apparent from these results that the polymerization of the isobutylene has been very materially reduced by the use of the ammonium sulfate in the sulfuric acid catalyst. At the same time the percentage of isobutylene going to the alkylation of the phenol remains substantially the same and the percentage of alkylated phenol in the liquid end-product is modified very little. Thus by the use of a catalyst comprising sulfuric acid and ammonium sulfate according to our invention an end-product is obtained having a lower ratio of polymer'to alkylated phenol.

What we claim is:

1. A process for the production of mono-hydroxy phenolic compounds alkylated in the hydroxylated nucleus comprising heating a mixture of an olefin and a mono-hydroxy phenolic compound in the presence of a solution of an alkali sulfate in sulfuric acid.

Unreacted isobutylene and 2. A process for the production of mono-hydroxy phenolic compounds alkylated in the hydroxylated nucleus comprising heating under pressure a mixture of an olefin and a mono-hydroxy phenolic compound in the presence of a solution of an alkali sulfate in sulfuric. acid.

- 3. A process for the production of mono-hydroxy phenolic compounds alkylated in the hydroxylated nucleus comprising heating at a temperature above about 100 C. a mixture of an olefin and a mono-hydroxy phenolic compound in' the presence of a solution of an alkali sulfate in sulfuric acid.

4. A process for the production of mono-hytact with a solution of an alkali sulfate in sulfuric acid.

6. A process for the production of 2,6-ditertiary-butyli-phenyl-phenol comprising heating at a temperature of about 150 C. a mixture containing isobutylene and para-hydroxy-diphenyl in contact with a solution of sulfuric acid about 60 per cent saturated with ammonium sulfate.

DONALD R. STEVWS. JOSEPH E. NIC" 

